Global Solutions for the Food Industry

How to use a Vacuum Fryer Machine for Fruit Chips

Vacuum frying makes crispy, low-oil fruit chips by dehydrating fruit at 70–110°C under vacuum (-0.07 to -0.095 MPa). Below is a step-by-step guide.
 
 

1. Principle & Advantages

 
  • Lower boiling point: Water boils at ~40–60°C under vacuum, so fruit dehydrates at low temperatures.
  • Benefits:
    • Retains color, flavor, and vitamins (less oxidation).
    • Crispy texture with 15–25% oil content (vs. 40–50% in regular frying).
    • No burnt taste or acrylamide formation.
     
 
 

2. Raw Material Selection

 
Choose fruits with:
 
  • Firm flesh, moderate ripeness, and high dry matter.
  • Examples: apple, banana, kiwi, pineapple, pear, peach, strawberry.
 
 

3. Pre-Treatment (Critical for Quality)

 

Step 1: Cleaning & Peeling

 
  • Wash thoroughly; peel/remove seeds/core as needed.
 

Step 2: Slicing

 
  • Cut into 2–4 mm uniform slices (even heating).
 

Step 3: Color Protection (Anti-Browning)

 
  • Soak slices in solution: 0.5–1% salt + 0.2–0.5% citric acid for 5–10 mins.
 

Step 4: Blanching (Enzyme Deactivation)

 
  • Dip in 60–80°C hot water for 2–6 mins (locks color, softens tissue).
 

Step 5: Sugar Infusion (Optional, for Sweetness & Crispness)

 
  • Soak in 20–30% sugar syrup for 30–60 mins (reduces oil uptake).
 

Step 6: Draining & Pre-Freezing

 
  • Drain excess water; freeze at -18°C for 4–12 hrs (forms ice crystals for better puffing).
 
 

4. Vacuum Fryer Operation

 

Step 1: Machine Preparation

 
  1. Clean the frying tank, basket, and oil filter.
  2. Fill with food-grade palm oil or sunflower oil (covers basket, 80% of tank capacity).
  3. Turn on power; set parameters:
    • Temperature: 80–100°C (apple: 85–90°C; banana: 80–85°C).
    • Vacuum: -0.08 to -0.09 MPa.
    • Time: 15–30 mins (depends on thickness and fruit type).
     
  4. Preheat oil to target temperature.
 

Step 2: Loading & Frying

 
  1. Place frozen fruit slices in a single layer in the frying basket.
  2. Lower basket into oil; seal the tank door tightly.
  3. Start the vacuum pump; evacuate until pressure reaches -0.08 MPa.
  4. Frying process:
    • Water evaporates rapidly; oil bubbles vigorously at first.
    • When bubbling slows (most moisture removed), continue frying for 5–10 mins until chips are crisp.
     
 

Step 3: Vacuum De-Oiling

 
  1. Lift basket from oil; keep vacuum on (-0.07 to -0.08 MPa).
  2. Start centrifugal de-oiling (300–500 rpm, 5–10 mins) to remove surface oil.
  3. Release vacuum; open the tank door.
 
 

5. Post-Processing

 
  1. Cooling: Spread chips on a clean tray; cool to room temperature in a dry, cool area.
  2. Seasoning (Optional): Add salt, sugar, cinnamon, or fruit powder in a seasoning drum.
  3. Packaging: Seal in moisture-proof, airtight bags (use nitrogen flushing for longer shelf life).
 
 

6. Key Parameters for Common Fruits

 
 
 
 
FruitSlice ThicknessTemp (°C)Vacuum (MPa)Time (mins)
Apple2–3 mm85–90-0.0818–25
Banana3–4 mm80–85-0.0815–20
Kiwi2–3 mm85–90-0.0820–25
Pineapple3–4 mm90–95-0.0825–30
 
 

7. Troubleshooting

 
  • Soggy chips: Insufficient drying; extend frying time or increase vacuum.
  • Too oily: Incomplete de-oiling; increase centrifugal time or speed.
  • Discoloration: Poor color protection; add more citric acid or reduce pre-freezing time.
  • Burnt edges: Temperature too high; lower by 5–10°C.
 
 

8. Machine Maintenance

 
  • Filter oil after each use; replace every 50–100 batches.
  • Clean the vacuum pump and condenser regularly to remove residue.
  • Check seals and valves for leaks before each run.
 
 
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